The present invention relates to a fixation clamp and, more particularly, to a fixation clamp for use in an external fixation system for holding bone fragments adjacent each other. External fixation systems are widely used to connect two or more bone fragments to each other. Such systems comprise bone screws, pins, wires which are inserted directly into the bone material and these systems use external structural elements as fixation rods, bars and rings. In order to connect the rods and bars to form a rigid frame, fixation clamps are used. Furthermore, fixation clamps are used to connect the screws and pins to the rigid frame to specifically hold bone fragments at an intended place.
One adjustable fixation clamp is known from U.S. Pat. No. 6,080,153 comprising two pairs of jaws allowing clamping of a rod as well as of a pin.
A clamp for multiple rod-shaped elements is known from U.S. Pat. No. 7,618,417 having one single pair of jaws. However, such a clamp allows clamping more than two, e.g. three or four rod-shaped elements as pins with one single clamp, thus reducing the number of clamps. However, one further fixation clamp is necessary to fix the rod of said clamp to the frame of the fixation system.
U.S. Patent Application Publication No. 2006/0287652 mentions that usual fixation clamps as e.g. known from U.S. Pat. No. 6,080,153 allow clamping of one single screw or pin to the frame. This way of attaching pins or rods leads to bulky fixation systems. Therefore 2006/0287652 discloses a fixation clamp addressing this problem and comprises two pairs of jaws within which each pair of jaws allows the introduction and clamping of two rods or pins etc. at the same time.
These clamps according to the prior art either provide different diameters of the reception openings provided by the jaws to introduce different sizes of rods, pins or wires, or they rely on additional inserts as e.g. disclosed in U.S. Publication 2008/0065068. Such inserts reduce the diameter of the reception cavities to allow a secure fixing of differently sized rods, pins or wires.
From U.S. Publication 2010/0298827 a further fixation clamp is known. The disclosure of U.S. 2010/0298827 is incorporated herein by reference. Users feel very comfortable with the fixation clamp according to this design. However, past use has shown that in some applications the jaws of the clamping assembly have been orientated in an erroneous manner which led to unsatisfactory results. Hence there is a need to have a fixation clamp with which erroneous alignment of the jaws is prevented.